U01.01.063 Vitamin A

Key Components of Vitamin A

Antioxidant Properties: Protects cells from oxidative damage.
Visual Function: Constituent of visual pigments (retinal).
Cellular Differentiation: Promotes normal differentiation of epithelial cells into specialized tissues (e.g., pancreatic cells, mucus-secreting cells).
Prevention of Squamous Metaplasia: Maintains epithelial tissue integrity.
Therapeutic Uses:
- Treats measles and acute promyelocytic leukemia (APL).
- Oral isotretinoin for severe cystic acne.
- All-trans retinoic acid for APL.

Symptom	Description
Night Blindness	Impaired vision in low light (nyctalopia).
Dry, Scaly Skin	Xerosis cutis.
Corneal Changes	– Squamous metaplasia.
	– Bitot spots (foamy keratin debris on conjunctiva).
	– Corneal degeneration (keratomalacia).
Immunosuppression	Increased susceptibility to infections.

Type	Manifestations
Acute	Nausea, vomiting, vertigo, blurred vision.
Chronic	Alopecia, dry skin (scaliness), hepatic toxicity and enlargement, arthralgias, intracranial hypertension.
Teratogenic	Cleft palate, cardiac abnormalities. Requires negative pregnancy test and two forms of contraception before isotretinoin prescription.

Mnemonic:
- Retinol = Vitamin A. Think retin-A (used for wrinkles and acne).
Supplementation:
- Beneficial in measles patients with vitamin A deficiency to improve outcomes.
Teratogenicity:
- Isotretinoin (a derivative) is highly teratogenic. Ensure pregnancy prevention measures before use.
Clinical Application:
- Know the specific uses of vitamin A derivatives (e.g., isotretinoin for acne, all-trans retinoic acid for APL).